Background: Increased number of intestinal intraepithelial lymphocytes (IELs) is a key histological finding in the diagnosis of celiac disease (CD); however, the number of IELs in celiac patients and healthy subjects may vary from one region to another. Additionally, there are some seronegative celiac patients with a borderline histology. Objective: To determine the number of the CD3⁺ and CD8⁺ IELs T-cells in the celiac patients and healthy subjects (controls) in Isfahan. Methods: The duodenal biopsies were obtained from the celiac patients (n=15) and the controls (n=19). The total number of IELs/100 epithelial cells (ECs) were counted using the hematoxylin-eosin (H&E) staining method, and that of CD3⁺ and CD8⁺ IELs/100 ECs were counted using the immunohistochemistry (IHC) staining method. Results: This study defined the upper normal limit for each variable as mean + 2SD. Accordingly, the upper normal limits of the total IELs, CD3⁺ IELs, and CD8⁺  IELs/100 ECs were calculated as 37 (95% confidence intervals, CI: 33–41), 22 (95% CI: 19–25) and 12 (95% CI: 10–14), respectively. In 3 clinically CD diagnoses, the total IELs counts/100 ECs were below the upper normal limit, and the histopathological and serologic assays were negative. Nevertheless, the CD8⁺ IELs T-cells counts/100 ECs showed borderline values. Interestingly, these patients responded to a gluten-free diet (GFD). Conclusions: The study findings suggest that in the clinically diagnosed celiac disease, IELs count/100 ECs below the upper normal limit as well as negative histopathological and serologic assays and the cell density counts of the CD8⁺ IELs T-cells/100 ECs could be a useful parameter for CD diagnosis and make a decision to put them on a GFD.